FR3085063A1 - TORQUE TRANSMISSION DEVICE COMPRISING A STARTING TOOTH AND A TARGET - Google Patents

Abstract

The invention relates to a torque transmission device for a motor vehicle transmission chain comprising: - a rotary element (5) intended to be mounted in rotation about an axis of rotation X comprising a cylindrical skirt (6) having a axial orientation; - a one-piece ring (2) which is arranged circumferentially around the cylindrical skirt (6) and which is fixed thereto; said ring (2) having, on the one hand, a first annular zone in which is formed a starting toothing (3) intended for the rotary drive of the torque transmission device (1) and on the other hand, a second annular zone in which a target (4) is arranged intended to be arranged opposite a sensor capable of delivering a signal representative of the angular position and / or of the speed of rotation of the target (4).

Description

Technical area

The invention relates to the field of motor vehicle transmission chains and relates more particularly to a torque transmission device for a motor vehicle transmission chain which is equipped, on the one hand, with a target intended to be arranged in look of a sensor and, on the other hand, of a starting toothing.

Technological background

In the prior art, there are known torque transmission devices, of the flywheel type or double damping flywheel for example, which are equipped, on the one hand, with a starting crown and, on the other hand , of a target intended to be placed opposite a sensor delivering a signal representative of the angular position and / or of the speed of rotation of the target.

The starter ring is generally obtained by bending a steel bar so that its two ends can be butt welded and then machining the steel bar thus bent in order to form a toothing on its outer periphery.

Furthermore, the target is a part obtained by cutting and stamping. The target has a plurality of fingers which extend parallel to the axis of rotation of the torque transmission device and which separate from one another the windows distributed around the X axis. Thus, when the transmission device of torque is driven in rotation around the X axis, the fingers generate variations in the magnetic field capable of being detected by a sensor positioned opposite the target.

The aforementioned devices are not, however, fully satisfactory.

In fact, the start-up crown and the target are made up of two separate parts, which complicates the manufacture and assembly of the torque transmission device.

In addition, the manufacture of the target and more particularly of its fingers is subject to extremely restrictive tolerances, in particular in order to ensure the reliability of the signal delivered by the sensor. However, the known methods of manufacturing the target do not allow the required levels of precision to be achieved.

summary

An idea underlying the invention is to propose a torque transmission device for a motor vehicle transmission chain, equipped, on the one hand, with a starting toothing capable of ensuring the starting of the engine and, d on the other hand, a target, which is easier to manufacture.

According to one embodiment, the invention provides a torque transmission device for a motor vehicle transmission chain comprising:

- a rotary element intended to be mounted for rotation about an axis of rotation X comprising a cylindrical skirt having an axial orientation;

- A one-piece ring which is arranged circumferentially around the cylindrical skirt and which is fixed to the latter; said ring having, on the one hand, a first annular zone in which is formed a starting toothing intended for the rotary drive of the torque transmission device and on the other hand, a second annular zone in which is formed a target intended to be placed opposite a sensor capable of delivering a signal representative of the angular position and / or the speed of rotation of the target.

Thus, the starting teeth and the target are made in one piece. Such a torque transmission device is therefore simpler to manufacture, in particular in that the number of parts to be assembled for its manufacture is limited.

According to other advantageous embodiments, such a torque transmission device can have one or more of the following characteristics:

According to one embodiment, the first and second annular zones are separated axially from one another by a circular median annular zone.

According to one embodiment, the starting teeth and the target are machined in the ring. Thus, the machining of the target allows, relative to a target formed by a stamping process, to reduce the manufacturing tolerances of the target.

According to one embodiment, the ring is fixed to the cylindrical skirt by a tight fitting.

According to one embodiment, the ring is welded to the cylindrical skirt.

According to one embodiment, the cylindrical skirt has an outer periphery having a shoulder defining a first bearing surface and the ring has an outer periphery having a shoulder defining a second bearing surface, the first and the second bearing surfaces being in abutment against one another so as to guarantee a determined axial positioning of the ring on the cylindrical skirt.

According to one embodiment, the rotary element comprises a radial portion having an external periphery from which the cylindrical skirt extends axially and a cover which is welded to the cylindrical skirt so as to define with the radial portion and the skirt cylindrical an annular chamber, the cover having an external periphery protruding radially beyond the cylindrical skirt and forming a bearing surface against which the ring is supported so as to guarantee a determined axial positioning of the ring on the cylindrical skirt .

According to one embodiment, the ring and the cylindrical skirt have a polarizing device making it possible to ensure a determined relative angular positioning of the ring with respect to the rotary element.

According to one embodiment, the polarizing device comprises a finger and a groove respectively formed in the ring and the cylindrical skirt or vice versa, said finger being housed in said groove.

According to one embodiment, the ring is obtained by bending a steel bar having two ends and by welding said two ends to each other. Such a ring thus makes it possible to increase the inertia associated with the rotary element, which is desirable for certain applications.

According to one embodiment, the invention provides a method of manufacturing a torque transmission device comprising:

- provide a rotary element intended to be mounted for rotation about an axis of rotation X comprising a cylindrical skirt having an axial orientation;

- Manufacture a one-piece ring having, on the one hand, a first annular zone in which is formed a starting toothing intended for the rotary drive of the torque transmission device and on the other hand, a second annular zone in which is formed a target intended to be arranged opposite a sensor capable of delivering a signal representative of the angular position and / or the speed of rotation of the target; and

- fix the monobloc ring circumferentially around the cylindrical skirt.

According to one embodiment, the ring is fixed to the cylindrical skirt by a tight fitting, for example by a hot fitting.

According to another embodiment, the ring is welded to the cylindrical skirt.

According to one embodiment, the ring is obtained by bending a steel bar having two ends, by welding said two ends to each other and by machining the starting teeth and the target in the steel bar.

According to one embodiment, the invention also provides a motor vehicle comprising a said torque transmission device.

Brief description of the figures

The invention will be better understood, and other objects, details, characteristics and advantages thereof will appear more clearly during the following description of several particular embodiments of the invention, given solely by way of illustration and without limitation. , with reference to the accompanying drawings.

- Figure 1 is a partial perspective view of a double damping flywheel equipped with a one-piece ring in which are formed a starting toothing and a target.

- Figure 2 is a partial half-view in section of the double damping flywheel of Figure 1.

- Figure 3 is a detailed sectional view illustrating the primary flywheel and the monobloc ring in which are formed a starting toothing and a target according to a second embodiment.

- Figure 4 is a perspective view of a primary flywheel of a double damping flywheel according to a third embodiment before the ring including the starting teeth and the target is fixed to said primary flywheel.

FIG. 5 is a perspective view of the ring, including a starting toothing and a target, intended to be mounted on the primary flywheel of FIG. 4.

- Figure 6 is a partial sectional view of a double damping flywheel according to a fourth embodiment.

Detailed description of embodiments

In the description and the claims, the terms external and internal as well as the axial and radial orientations will be used to designate, according to the definitions given in the description, elements of the torque transmission device. By convention, the radial orientation is directed orthogonally to the axis X of rotation of the torque transmission device determining the axial orientation and, from the inside to the outside away from said axis, the circumferential orientation is directed orthogonally to the axis of the torque transmission device and orthogonally to the radial direction. The terms external and internal are used to define the relative position of one element with respect to another, with reference to the axis X of rotation of the torque transmission device, an element close to the axis is thus qualified as internal as opposed to an external element located radially on the periphery. Furthermore, the terms rear AR and front AV are used to define the relative position of one element with respect to another in the axial direction, an element intended to be placed close to the heat engine being designated by rear and an element intended to be placed close to the gearbox being designated by front.

In connection with FIGS. 1 and 2, there is a torque transmission device 1 of a transmission chain which is equipped with a ring 2 in which are formed, on the one hand, a starting toothing 3 intended when driving the torque transmission device 1 in rotation and, on the other hand, a target 4 intended to be placed opposite a sensor capable of delivering a signal representative of the angular position and / or the speed of target rotation 4.

The torque transmission device 1 comprises a rotary element which is intended to be secured in rotation to the transmission chain and which comprises a cylindrical skirt 6 of axial orientation around which the ring 2 is circumferentially disposed.

In the embodiment shown, the torque transmission device 1 is a double damping flywheel. Also, the torque transmission device 1 comprises a primary flywheel 5, a secondary element, not shown, which is mounted movable in rotation relative to the primary flywheel 5 around the axis X and elastic members 7, shown in FIG. 2, which are arranged to transmit a torque and dampen the acyclisms between the primary flywheel 5 and the secondary element. Note, however, that the invention can be applied to other types of torque transmission device 1 and in particular to a torque transmission device without torsion damper, such as a flywheel, rigid or flexible, by example.

The primary flywheel 5 comprises a hub 10, illustrated in FIG. 1, a radial portion 8 which extends radially outward from the hub 10 and a cylindrical skirt 6 of axial orientation which extends towards the front from the outer periphery of the radial portion 8. As illustrated in FIG. 1, the primary flywheel 5 is provided with holes 9 allowing the passage of fixing screws intended for fixing the primary flywheel 5 on the engine crankshaft.

The primary flywheel 5 also includes a cover 11, illustrated in FIG. 2, which is fixed to the front end of the cylindrical skirt 6. The cover 11 defines, with the radial portion 8 and the cylindrical skirt 6, a chamber annular 12 in which the elastic members are housed 7. The elastic members 7 are, for example, curved coil springs which are circumferentially distributed around the axis X. Each of the elastic members 7 extends circumferentially between two support legs a veil 13, shown in Figure 2, and two support seats carried by the primary flywheel 5. Each support seat carried by the primary flywheel 5 is, for example, constituted by two bosses which are respectively formed in the radial portion 8 of the primary flywheel 5 and in the cover 11. A boss 14 formed in the radial portion 8 of the primary flywheel 5 is notably rep shown in Figure 1.

The secondary element is, for example, a secondary flywheel intended to form the reaction plate of a clutch, not shown, connected to the input shaft of a gearbox. The secondary element is centered and guided on the primary element by means of a bearing, not shown, such as a ball bearing for example. According to an alternative embodiment, the web 13 is fixed to the secondary element. According to another variant, the web 13 is not directly fixed to the secondary element but is movable in rotation around the axis X relative to said secondary element. In this case, the torque is transmitted between the web 13 and the secondary element by one or more additional stages of elastic members.

In operation, each of the elastic members 7 bears, at a first end, against a support seat carried by the primary flywheel 5 and, at a second end, against a support lug, not shown, carried by the web 13, so as to ensure the transmission of the torque between the primary flywheel 5 and the secondary element.

As shown in Figures 1 and 2, the ring 2 is a single piece in which are machined, on the one hand, a starting toothing 3 and, on the other hand, a target 4. The starting toothing 3 and the target 4 are formed on the outer periphery of the ring 2 respectively in a first annular zone z1 and a second annular zone z2. In the embodiment shown, the first annular zone z1 in which the starting toothing 3 is formed is arranged at the rear of the second annular zone z2 in which the target 4 is formed. However, according to another alternative embodiment, the layout is reversed. As shown in FIG. 2, the first and second annular zones z1, z2 are separated from each other by a circular median annular zone z3.

The starting toothing 3 is intended for driving the primary flywheel 5 in rotation so as to ensure the starting of the engine. The starting toothing 3 is, to do this, intended to mesh with a starter.

The target 4 comprises a plurality of notches 15 which are regularly distributed around the axis X and which are separated from each other by projections 16 each extending in the axial direction, parallel to the axis X.

Such a structure formed by alternating notches 15 and projections 16 allows a sensor which is fixed to a non-rotating element of the vehicle, such as for example the engine block or the casing of the vehicle gearbox, and which is positioned radially opposite the target 4 to detect the position and / or speed of the target 4. To do this, in an advantageous embodiment, the ring 2 and therefore the target 4 is made of a magnetic material, such as than steel. In addition, the sensor is able to detect variations in magnetic fields. Such a sensor is for example an active hall effect sensor or a passive sensor. Thus, the alternation of notches 15 and projections 16 is capable of generating, when the target 4 is driven in rotation, a variation in magnetic field which is detected by the sensor. In another embodiment, the sensor is an optical sensor which detects the passage of a notch or a projection in its optical field.

Advantageously, as shown in FIG. 1, at least one of the notches, referenced 17 in FIG. 1, has a circumferential dimension different from that of the other notches 15. Such a notch 17 constitutes a mark making it possible to determine the position angular of the target 4. Alternatively, such a mark can also be formed by a projection 16 having a dimension in the circumferential direction greater than that of the others. The reference may in particular be a top dead center reference, that is to say that it is located opposite the sensor when the position of the crankshaft is such that the engine piston closest to the nose of the crankshaft is located high position.

According to one embodiment, the ring 2 is obtained by bending a steel bar so that its two ends can be butt welded and then machining the steel bar thus bent in order to form the toothing on its outer periphery. 3 and target 4.

In the embodiment shown in Figures 1 and 2, the ring 2 is secured to the primary flywheel 5 by a tight fitting of the ring 2 on the cylindrical skirt 6 of the primary flywheel 5. According to an example of embodiment, the ring 2 is hot-pressed.

Advantageously, the ring 2 is fitted on the cylindrical skirt 6 from the rear to the front and the cover 11 of the primary flywheel 5 has an external periphery 18 protruding beyond the external surface of the skirt cylindrical 6. Thus, the outer periphery 18 of the cover 11 forms an abutment surface making it possible to guarantee precise axial positioning of the ring 2 relative to the primary flywheel 5.

In the embodiment shown in Figure 3, the cylindrical skirt 6 has a shoulder 19 formed on its outer periphery and the ring 2 has a complementary shoulder 20 formed on the inner periphery of the ring 2. Thus, when the ring 2 is fitted on the cylindrical skirt 6 of the primary flywheel 5, the shoulders 19, 20 form bearing surfaces 21, 22 of radial orientation which bear against one another so as to guarantee an axial positioning precise relative of the ring 2 with respect to the primary flywheel 5.

In the embodiment illustrated in FIG. 3, the ring 2 is fitted from the rear towards the front on the cylindrical skirt 6 of the primary flywheel 5. Also, the extra thickness providing the shoulder 19 of the flywheel primary inertia 5 is disposed at the front of the bearing surface 21 of said shoulder 19 while the additional thickness providing the shoulder 20 of the ring 2 is disposed at the rear of the bearing surface 22 of said shoulder 20.

In another embodiment, not shown, the ring 2 is fitted from the front to the rear on the cylindrical skirt 6 of the primary flywheel 5. Consequently, the arrangement of the shoulders 19, 20 is reversed. In other words, the additional thickness providing the shoulder 19 of the primary flywheel 5 is disposed at the rear of the bearing surface 21 of said shoulder 19 while the additional thickness providing the shoulder 20 of the ring 2 is disposed at the front of the bearing surface 22 of the corresponding shoulder 20.

Figures 4 and 5 illustrate a primary flywheel 5 and a ring 2 according to another embodiment. In this embodiment, the primary flywheel 5 and the ring 2 have a polarizing device making it possible to ensure a determined relative angular positioning of the ring 2 relative to the primary flywheel 5. In FIGS. 4 and 5 , the polarizing device has a groove 23, shown in FIG. 4, which is formed on the external periphery of the cylindrical skirt 6 of the primary flywheel 5. The polarizing device further comprises a finger 24, shown in the Figure 5, which is formed in the inner periphery of the ring 2 and which projects inwardly relative to the inner periphery of the ring 2. The finger 24 has a shape complementary to that of the groove 23 and is thus adapted to be housed therein when the ring 2 is fitted onto the cylindrical skirt 6 of the primary flywheel 5.

In another alternative embodiment, the structure is reversed, the finger 24 being formed on the outer periphery of the cylindrical skirt 6 of the primary flywheel 5 and the corresponding groove 23 being formed on the inner periphery of the ring 2. Note that the polarizing device is likely to have many other embodiments.

FIG. 6 illustrates a double damping flywheel according to another embodiment. This embodiment differs from that described in relation to Figures 1 and 2 in that the ring 2 is not fixed by a tight fitting on the cylindrical skirt 6 but is welded to it. In FIG. 6, two weld beads 25, 26 connecting the internal periphery of the ring 2 and the external periphery of the cylindrical skirt 6 are produced respectively at the front edge and the rear edge of the cylindrical skirt 6. Alternatively , only one of the two aforementioned two cords 25, 26 can be produced in order to secure the ring 2 to the primary flywheel.

Although the invention has been described in connection with several particular embodiments, it is obvious that it is in no way limited thereto and that it includes all the technical equivalents of the means described as well as their combinations if these are within the scope of the invention.

In particular, if the invention has been described above in relation to a double damping flywheel, a monobloc ring 2 integrating a target 4 and a starting toothing 3 as described above can also be associated with other types a torque transmission device, such as a rigid or flexible flywheel, a torque converter or the like.

The use of the verb "behave", "understand" or "include" and its conjugate forms do not exclude the presence of other elements or steps than those set out in a claim.

In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

Claims (10)

1. Torque transmission device for a motor vehicle transmission chain comprising: - a rotary element (5) intended to be mounted in rotation about an axis of rotation X comprising a cylindrical skirt (6) having an axial orientation; - a one-piece ring (2) which is arranged circumferentially around the cylindrical skirt (6) and which is fixed thereto; said ring (2) having, on the one hand, a first annular zone in which is formed a starting toothing (3) intended for the rotary drive of the torque transmission device (1) and on the other hand, a second annular zone in which a target (4) is arranged intended to be placed opposite a sensor capable of delivering a signal representative of the angular position and / or of the speed of rotation of the target (4). 2. Torque transmission device according to claim 1, in which the starting teeth (3) and the target (4) are machined in the ring (2). 3. Torque transmission device according to claim 1 or 2, wherein the ring (2) is fixed to the cylindrical skirt (6) by a tight fitting. 4. Torque transmission device according to claim 1 or 2, wherein the ring (2) is welded to the cylindrical skirt (6). 5. Torque transmission device according to any one of claims 1 to 4, in which the cylindrical skirt (6) has an external periphery having a shoulder (19) defining a first bearing surface (21) and the ring ( 2) has an outer periphery having a shoulder (20) defining a second bearing surface (22), the first and second bearing surfaces (21, 22) being in abutment against one another so as to guarantee a determined axial positioning of the ring (2) on the cylindrical skirt (6). 6. Torque transmission device according to any one of claims 1 to 4, in which the rotary element (5) comprises a radial portion (8) having an external periphery from which the cylindrical skirt (6) s' extends axially and a cover (11) which is welded to the cylindrical skirt (6) so as to define with the radial portion (8) and the cylindrical skirt (6) an annular chamber (12), the cover (11) having a outer periphery (18) protruded radially beyond the cylindrical skirt (6) and forming a bearing surface against which the ring (2) is supported so as to guarantee a determined axial positioning of the ring (2) on the cylindrical skirt (6). 7. Torque transmission device according to any one of claims 1 to 6, in which the ring (2) and the cylindrical skirt (6) have a polarizing device (23, 24) making it possible to ensure a determined relative angular positioning. of the ring (2) relative to the rotary element (5). 8. Torque transmission device according to claim 7, in which the polarizing device comprises a finger (24) and a groove (23) respectively formed in the ring (2) and the cylindrical skirt (3) or vice versa, said finger ( 24) being housed in said groove (23). 9. Torque transmission device according to any one of claims 1 to 8, in which the ring (2) is obtained by bending a steel bar having two ends and by welding said two ends to each other. . 10. Method for manufacturing a torque transmission device comprising: - provide a rotary element (5) intended to be mounted for rotation about an axis of rotation X comprising a cylindrical skirt (6) having an axial orientation; - Manufacture a one-piece ring (2) having, on the one hand, a first annular zone in which is formed a starting toothing (3) intended for the rotary drive of the torque transmission device and on the other hand, a second annular zone in which a target (4) is arranged intended to be arranged opposite a sensor capable of delivering a signal representative of the angular position and / or of the speed of rotation of the target (4); and - fix the monobloc ring (2) circumferentially around the cylindrical skirt.